I'd like to know if you want to learn character animation or if you want to make animated films. Because if you want to do character animation you'll want to learn the principles of animation, body mechanics, and general workflow. For this people generally recommend books like the animator's survival guide and the illusion of life. On youtube you can find Aaron Blaise and Toniko Pantoja, they usually talk about this stuff. On the other hand, if you want to create shorts, I'd recommend you to start learning how to write and storyboard, picking camera angles that aid in the telling of the story, understanding how to use music and editing to elevate the emotion of a scene, etc. For this, I'd recommend checking these out: https://www.radhowtoclass.com/projects It's not a hard dichotomy but it's good to start with a priority in mind.